Dendritic cells (DC) have the most efficient antigen-presenting function among antigen-presenting cells (collagen PC) in the body. The dendritic cells not only can express richly MHC-I molecules, MHC-II molecules, costimulatory molecules, adhesion molecules and high level Th1 type response predominant factor IL-12 respectively, but also can effectively activate homologous lymphocytes to generate antigen specific immune responses, which has become the focus in the field of tumour biotherapy recently. One key problem is how to enable the DCs to effectively present the tumour antigens. In recent years, people have tried to use different tumour antigens such as polypeptides, tumour cell lysates, tumour cell apoptosis products, etc, or to use gene engineering to transfer tumour antigen genes into the DCs by carriers. Sensitized DC vaccines can induce to form CTL cells in vivo and vitro and stimulate effective specific anti-tumour immune function within human body. Also, the sensitized DC vaccines have been proved to be effective for therapeutic trial of malignant tumour. However, in view of the fact that few antigens have been known so far, most of the tumour antigens are unknown. Thus scientists directly fuse the DCs with tumour cells, so that the DCs are ensured to express and present a variety of antigens on the basis of obtaining all the genes of the tumour cells, as well as to induce polyclonal immune response resisting to a wide variety of tumour antigens (including known and unknown one(s)), which has shown an exciting curative effect on tumour.
When the DCs directly fuse with the tumour cells, relatively low fusion efficiency has always been a difficult issue during research, and thus how to improve the fusion efficiency needs to be solved urgently. At present, three kinds of existing research methods can be used for inducing cell fusion: biological method (e.g., virus induced fusion method), chemical method (e.g., polyethylene glycol (PEG) induced fusion method), and physical method (e.g., electric field induced fusion method). There are a number of problems when using inactivated viruses to induce cell fusion, such as difficult preparation for viruses, complex operation, large difference of inactivated virus titer, poor reproducibility of experiments, and low fusion rate, etc. Because virus induced cell fusion has too many disadvantages, PEG induced cell fusion has gradually developed into a normative and important chemical fusion method since 1975. The advantage of the PEG method is that there is no specificity or selectivity between species, between genera or between families, so the PEG method has been still in use today. The PEG method has been widely used in many experiments with its low experimental cost and high fusion rate. Though there are lots of successful reports about PEG used as a fusion agent, there are still defects of low fusion rate and large empirical property.